The silvery fish is lying on the slab bleeding an astonishing red, half its head and side missing, but somehow not yet dead, like something tortured in Game of Thrones. Organs pulse. All around gasping dying fish are dumped on trays for display. In the steaming heat of Hong Kong's "wet" and "dry" markets, food shoppers prize fresh death over galloping decay.

Bass, carp, exquisite turbot, live out their last anxious moments before being dispatched and thrust into shopping bags. Clams of every sort and size, prawns, crabs, other exotic crustaceans spill on to the streets. Everywhere there is abalone, Asia's most prized shellfish.

Roasted ribs and belly pork with sublime crisp and fatty skin is packed for world class take-aways (the Chinese are maybe the most refined roasters of meat on the planet – though our British climate is just too wet and wrong, they explain pityingly). But the stall selling pigs' feet also has a table piled with service station sandwiches – rubber cheese and tomato, white slice – as though we are not here in Hong Kong but at a UK roadside stop.

Meat stalls punctuate the streets. Everything is eaten: lungs, liver, heart, tripe, huge splayed ribs of beef, slabs of hacked and bloody scarlet flesh, oxtail with or without its grubby hide. Fergus Henderson would be happy.

I marvel at the forests of green vegetables: fat broccoli stacked like timber logs, amaranths, spinaches, morning glory, all fresh in from the nearby New Territories, with local tomatoes and amethyst aubergine.

Next stop is a "dry" stall, where it is hard to differentiate between "medicine" and food. Here the air is musty, mysterious, fragrant with desiccated fish, spice and pet shop. Stacks of giant jars are packed with preserved abalone, curious black sea cucumbers, too, though these are not nearly as strange as the lizards splayed on sticks like alien lollipops.

We head inside the covered market, past the obscene eels swirling around their crowded bucket, the terrapins and turtles in washing-up bowls waiting to be made into soup and their sought-after meat to be gouged from their shell. Cages of concerned frogs, farmed to optimum size, are piled four or five deep. Their eyes follow me and seem to plead as I pass. Next, a gore-smeared live-chicken stall where your bird (white or black-skinned) is slaughtered and butchered in front of you, though this is officially discouraged since the pandemic of Asian avian flu.

Upstairs are the market cafes where shoppers and chefs come to eat. "Blood-tofu" (congealed bricks of pigs' blood) in noodle soup for breakfast: cheap iron-rich protein for a table of old ladies sucking on broth, while tables of younger couples tuck into their British-style bacon and eggs.

Hungry, I head to the ferry for Macau. Easier to get into than Hong Kong, where mainlanders still need a visa, Macau feels somehow more authentically Chinese, less laced with fading British influence and banking expats. Here, wage slaves come to lose their salaries and savings in the gambling rooms and casinos.

Here, too, of course, the ubiquitous international luxury stores, Hermès, Louis Vuitton, Dior, Chanel, all shiny and seductive. It seems many aspirational Chinese have fallen out of love with their own culture, and "Continental" is the look of the day. Macau has a curious rundown charm, like Las Vegas built by a Bollywood crew: witness the paint-peeling "Tibetan temple", the shoddy "volcano", and the Wynn and Sands casinos.

I had asked my companion, Susan Jung, food editor of the South China Morning Post, to take me to her favourite restaurant in the region. Half expecting (even hoping for) a secret roadside stall, I was surprised at first to be booked into the three-Michelin star Robuchon a Galera at the Hotel Lisboa. Ignoring the decor (posh French designed by a blind decorator, with twinkling star shapes on the ceiling), this is supremely accomplished cooking – as you'd expect from the most successful chef in the world – with flights of fine wine at a minuscule mark-up. As with all fine-dining places here, though, raw ingredients are mostly flown from Europe and the US – even the eggs are from New Zealand not the New Territories. The local and sustainable debate is not yet playing well in this part of the world.

Smart ladies lunch while their husbands or lovers lose their money. Most men here are not much interested in food except as fuel to keep them going while gambling.

Two floors but worlds away, a group of men loiter and leer while young prostitutes in pairs, holding hands, parade like ponies. (Everything in Macau is for sale, and prostitution is legal.) With bleached skin, bleached hair, newly bought breasts and barely out of their teens, they are peeled off one by one by greedy grubby men with darker appetites. The single girls not chosen look momentarily abandoned, afraid. I hurry past the pricey swallows' nests soup and shark fin shops and out into the rank sea air.

The next day I join a Hong Kong food tour with four of the city's oral obsessives. The brief: we eat local food from the best specialist places. From 90 options (I said they are obsessives) we narrow it down to six. Two of the group are packing serious cameras with fat and long lenses (here, bloggers are known to hump tripods and stepladders to restaurants to photograph food).

Over four or more hours we trawl their favourite Hong Kong tastes, some delicious, some less so. While I like the orange-spiked beef balls in broth in a "temporary" market, I love Osama Tony's turnip puffs: an exploding lard pastry packed with sweet root rendered in fat. But it is the beef brisket shop that divides us and where I learn a Hong Kong lesson: that in China, as in Japan, texture aces taste. From the three cuts we order (of nine), I favour the one with ragged scraps of meat while my companions prefer the grisly gristly bowls. The same happens at the next stall. I gorge on thin noodles larded with shrimp roe but shudder at the goose intestine which shares my plate, though I do make a weak-willed attempt at the grey tripe. A mistake.

While I override my gag reflex to swallow unseasoned stomach lining, one of our group gives an insight into Hong Kong food blogging. Keen to impress his Mongolian fiancee's family, he has signed up to kill a sheep in traditional style. This involves making a small cut behind the breast bone, inserting his arm into the chest cavity and crushing its heart with his hand. Blood must not be spilled, though that rule goes out the window when it comes to killing cows. A committed blogger, he has bought a camera helmet so the sheep's death can be streamed to the internet.

Feeling queasy, whether from his story, the humidity or the unforgiving offal, I trudge with diminishing enthusiasm to the silken tofu stall. Here, I find another exercise in texture-over-taste, but there is something quietly alluring about the slippery curd.

Our last stop restores my flagging faith and spirits. I could happily feast at Piggy Grill every week for the rest of my life. Suckling pig (the logo features a dancing piglet with a baby bottle) is split, slow roasted on a low heat then sugared and finished over a raging flame like someone blowing glass. Soft and succulent, sweet with rendered fat and luscious, crisp toffee skin, this may be the finest plate of pork I will ever eat.

Early the next morning I join chef Richard Ekkebus at the Aberdeen fish market, the floor awash with slippery algae and running water from hundreds of overflowing tanks. Here, you can see black crabs, mangrove crabs, typhoon crabs in season, and every species and size of fish including sluggish 4ft dorado crammed into 3ft tanks, and trays of abalone blowing bubbles. At the back, skyscraper blocks overshadow boats packed with live-in fishermen and prawn pots.

My favourite stop of the day, though, even the entire trip, is at Ngan Ki Heung on Queen's Road Central. Every inch of this exquisite tea shop is covered with caddies, bowls and tiny terracotta pots. Here, I finally find the Hong Kong of childhood dreams – the exotic harbour city of sea-going junks, porcelain and watercolour prints.

Be warned, they are not overly tourist-friendly, but if you are prepared to while away an hour they may sit you down and make you tea in a doll-service-size pot. The water will be at 98 degrees and from a pitcher with a cleansing mineral stone. The tea will be made meticulously, the first cup will be thrown away. Your bowl may contain green Iron Buddha or a densely flavoured oolong. It may be the best tea you will ever taste. Savour the gracious ceremony, drink your tea slowly. It will refresh, revive and ready you to face the turmoil of the city's streets yet again.